Name ACPI hardware IDs instead of magic _HID strings

Turn acpi-ids.zig's flat name table into a HardwareId enum modeled on
ps2-library's Port: one entry() switch holds the registry (variant ->
_HID string + human-readable name), with hid(), description(), and
fromHid() methods. The free description(hid) lookup the kernel's
device-tree dump uses survives, implemented over the enum, and a new
test round-trips every variant through fromHid.

Callers now name the device instead of quoting its id:

- ps2-library's DeviceType.hid() and ps2-bus's descriptor lookups use
  HardwareId.ps2_keyboard / .ps2_mouse.
- device-manager's driverFor parses the HID once with fromHid and
  switches on named values.
- acpi.zig's isPciRootNode carried the same ids twice, as strings and
  as packed-EISA integers (0x030AD041/0x080AD041); both branches now
  decode to the string form and answer through one isPciRootHid helper
  using .pci_bus / .pci_express_root_bridge.
- build.zig threads the acpi-ids module (previously kernel-only) into
  every user binary, like xkeyboard-config.

system/devices/acpi.zig

@@ -17,6 +17,7 @@
 const std = @import("std");
 const boot_handoff = @import("boot-handoff");
 const abi = @import("abi");
+const acpi_ids = @import("acpi-ids");
 const parameters = @import("parameters");
 const device_model = @import("device-model.zig");
 const aml = @import("aml/aml.zig");
@@ -914,7 +915,14 @@ fn readAdr(node: *aml.Node) ?u32 {
     return @truncate(readIntObj(n.value, &p) orelse return null);
 }
 
-/// Whether a namespace device is a PCI(e) host bridge (`PNP0A03` / `PNP0A08`).
+/// Whether a `_HID` string names a PCI(e) host bridge.
+fn isPciRootHid(hid: []const u8) bool {
+    const id = acpi_ids.HardwareId.fromHid(hid) orelse return false;
+    return id == .pci_bus or id == .pci_express_root_bridge;
+}
+
+/// Whether a namespace device is a PCI(e) host bridge. A packed EISA id is decoded
+/// to its string form first, so both encodings answer through the one registry.
 fn isPciRootNode(node: *aml.Node) bool {
     const hid = aml.Namespace.childOf(node, seg4("_HID")) orelse return false;
     if (hid.kind != .name or hid.value.len == 0) return false;
@@ -922,12 +930,10 @@ fn isPciRootNode(node: *aml.Node) bool {
         0x00, 0x01, 0xFF, 0x0A, 0x0B, 0x0C, 0x0E => {
             var p: usize = 0;
             const n = readIntObj(hid.value, &p) orelse return false;
-            return n == 0x030AD041 or n == 0x080AD041; // PNP0A03 / PNP0A08
-        },
-        0x0D => {
-            const s = cstr(hid.value[1..]);
-            return std.mem.eql(u8, s, "PNP0A03") or std.mem.eql(u8, s, "PNP0A08");
+            var buffer: [8]u8 = undefined;
+            return isPciRootHid(eisaIdToStr(@truncate(n), &buffer));
         },
+        0x0D => return isPciRootHid(cstr(hid.value[1..])),
         else => return false,
     }
 }